General purpose developer

ABSTRACT

A developer composition comprises three developing agents -- a 3-pyrazolidone, a dihydroxybenzene, and an enediol -- an inorganic sulfite preservative, a buffering agent, a silver halide solvent, a graininess reducing agent, and a restrainer. When adjusted to the pH range 8 to 9.5, the developing agent is effective to increase the exposure index of films by a factor of 3.2 - 4.2 while at the same time producing images having a good density range and good shadow detail.

O United States Patent 1 1 1111 3,865,591 Katz Feb. 11, 1975 [5 1 GENERAL PURPOSE DEVELOPER 3,615,513 10/1971 HaiSt et a1. 96/61 M 3,730,716 5 1973 L' d 96 29 R [75] Inventor: Jerome Katz, Rochester, N.Y. [73] Assignee: Delaware Photographic Products, Primary Examiner-Mary F. Kelley lnc., Buffalo, NY. Attorney, Agent, or Firm-Clarence A. OBrien; 22 Filed: May 10, 1973 Harvey [21] App]. No.: 358,936 [57] ABSTRACT A developer composition comprises three developing 521 US. Cl. 96/66.3, 96/66 R, 96/66 HD agents a -py a dihydroxybenzene. and 511 1111. c1 603C 5/30 an enediol an inorganic Sulfite preservative. 9 buff- [58] Field Of Search 96/66.3, 66 HD, 66 R ering agent, a Silver halide Solvent 9 graininess reducing agent, and a restrainer. When adjusted to the pH 5 References Cited range 8 to 9.5, the developing agent is effective to in- UNITED STATES PATENTS crease the exposure index of films by a factor of 3.2 2 685 515 H W1 96/66 3 4.2 while at the same time producing images having a 1son 3,276,875 10/1966 Schwalenstocker 1 96/66 R good denslty range and good Shadow detail 3,615,440 10/1971 Bloom 96/66 R 27 Claims, N0 Drawings GENERAL PURPOSE DEVELOPER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to silver halide photographic developer compositions and, more particularly, to developer compositions which increase the exposure index of film (EL).

2. Description of the Prior Art In general, low speed films produce better image characteristics, such as fine grain, whereas high speed films permit greater flexibility in use, albeit at the expense of image quality. No high speed film presently exists which can produce low speed image quality. Accordingly, efforts have been directed at producing silver halide developers which are capable of increasing the effective film speed of a film in the hope that fine grain films exposed at high speeds would still produce fine image quality. To date, no such developer has become available, it having been found that image characteristics, such as shadow detail, degenerate upon development in compositions which increase the El. of the film.

Although numerous developer compositions utilize developing agents which comprise various combinations of a 3-pyrazolidone, a dihydroxybenzene and an enediol, there appears to exist no such composition capable of increasing the exposure index of film while maintaining fine quality images. US. Pat. No. 3,276,875 to Schwallenstocker discloses a photographic paper developer composition (not a film developer) which utilizes a combined l-phenyl-3- pyrazolidonelhydroquinone/ascorbic acid developing agent in conjunction with an anti-sludging agent to improve image density. The Schwallenstocker developer employs a total of 46 grams per liter of developing agent in combination with other ingredients, including 8 grams per liter of benzotriazole anti-foggant. However, when the Schwallenstocker composition is used to develop commercially available film emulsions, notwithstanding the unusually large quantity of antifoggant, the negative is commercially unacceptable due to gross fog. To reduce the fog to acceptable levels requires the addition of additional anti-foggant until the benzotriazole concentration level reaches about 28 grams per liter. Although at a developer level of 46 grams per liter and an anti-foggant level of 28 grams per liter acceptable images can be produced without appreciable fog, it will be appreciated that such a developer composition is totally impractical. Thus the composition was diluted to a reasonable l-phenyl-3- pyrazolidone concentration level of about one gram per liter, at which level although development and fog were satisfactory, there was no increase noted in the exposure index of films developed therein.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a developer composition capable of increasing the exposure index of film.

It is another object of this invention to provide a developer composition which produces good image quality, such as fine grain and excellent shadow detail, at the increased exposure index values.

It is still another object of this invention to provide a photographic developing process for increasing the exposure index of black and white continuous tone commercially available negative silver halide film.

Other objects and advantages will become apparent from the following description and appended claims.

Briefly stated, in accordance with the aforesaid objects, the present invention in its preferred embodiment provides a developer composition comprising three de veloping agents a 3-pyrazolidone, a dihydroxybenzene, and an enediol an inorganic sulfite preservative, a buffering agent, a silver halide solvent, a graininess reducing agent, and a restrainer. When adjusted to the pH range 8 to 9.5, the developing agent is effective to increase the exposure index (E.l.) of films while at the same time producing images having a broad density range and good shadow detail.

As compared with other known 3-pyrazolidonedihydroxybenzene-enediol developer compositions, such as disclosed in US. Pat. No. 3,276,875 by Schwalenstocker, one essential difference is that the present composition employs an amount of dihydroxybenzene about five times greater (based on roughly equivalent concentrations of 3-pyrazolidone and enediol). Since dihydroxy-benzenes, such as hydroquinone, are well known contrast -or density building agents, it is surprising that the present developer formulation, using such a large amount of hydroquinone, could provide a wide range of tones and not suffer the disadvantages of high contrast results normally to be anticipated from the increased hydroquinone concentration. Furthermore, based upon the known characteristics of presently available speed building developers, it would be expected that to achieve shadow detail at increased exposure index values the well known shadow detail developing agents, such as metol, Phenidone (a trademark of Ilford, Ltd.) or amidol, would have to be employed in large quantities. According to the present invention, neither metol nor amidol are required, and Phenidone is employed in an amount that would seem to be too small to be effective in producing good shadow detail when films are exposed at higher than normal exposure index values. Surprisingly, the increase in dihydroxybenzene in the present developer not only increases exposure index by a factor of 3.2 4.2 but does so while still yielding fine grain and good shadow detail.

DETAILED DESCRIPTION OF THE INVENTION The present invention, in its broadest form, provides an alkaline developer composition, pH 8 to 9.5, containing at least three developing agents. Table 1 sets forth the ingredients and proportion ranges at which useful results, in terms of increased exposure index without adverse side effects, are obtained.

In addition, conventional hardeners, antifoggants, grain reducers, solubilizers, stabilizers, toners, buffers, antioxidants, sequestering agents and antisludge agents may be used in the developer composition. The opti- 4 16. l--chlorophenyl-4-methyl-4-ethyl-3- pyrazolidone l7. lrm-acetamidophenyl-4,4-diethyl-3-pyrazolidone l8. l-p-( B-hydroxyethylphenyl )-4,4'-dimethyl-3- mum results with the developer composition, in terms 5 pyrazolidone of increased speed index, acutance and graininess, was

found to be possible when the composition was adjusted to the pH range 8.3 to 8.75.

The silver halide developing agents employed in accordance with the present invention are selected, one

[1-K C-R .in which the R groups each represent various substitu- -bon atoms, or an aryl group such as phenyl.

l-phenyl-3-pyrazolidone (Phenidone) is the preferred member of the 3-pyrazolidone class of agents for use in the present invention. Phenidone is preferred because it is commercially availablein large quantities while other known, related developing agents having similar structure and characteristics are not widely available. The following compounds are representative of 3-pyrazolidone silver halide developing agents which are useful in the developer compositions of this invention:

1. l-phenyl-3-pyrazolidone 2. l-p-tolyl-3-pyrazolidone 3. 5-phenyl-3-pyrazolidone 4. pyrazolidone 5. l-p-chlor0phenyl-3-pyrazolid0ne '6. l-phenyl-5-phenyl-3-pyrazolidone 7. l-m-tolyl-3-pyrazolidone 8. l-phenyl-5-methyl-3-pyrazolidone 9. l-p-tolyl-5-phenyl-3-pyrazolidone l0. l-m-tolyl-3-pyrazolidone l l. l-p-methoxyphenyl-3-pyrazolidone l2. l-acetamidophenyl-3-pyrazolidone l3. l-phenyl-2-acetyl-4,4-dimethyl-3-pyrazolidone .14. 1-phenyl-4,4-climethyl-3-pyrazolidone l5. l-m-aminophenyl-4-methyl-4-propyl-3- pyrazolidone 5-methyl-3- I 19. l-p-hydroxyphenyl-4,4-dimethyl-3-pyrazolidone 20. l-p-methoxyphenyl-4,4-diethyl-3-p'yrazolidone 21. l-p-tolyl-4,4-dimethyl-3-pyrazolidone 22. l-( 7-hydroxy-2-napthyl )-4-methyl-4-n-propyl-3- pyrazolidone 23. l -p-diphenyl-4,4-dimethyl-3-pyrazolidone 24. l-p-(B-hydroxyethylphenyl)-3-pyrazolidone 25. l-o-tolyl-3-pyrazolidone 26. l-o-tolyl-4,4-dimethyl-3-pyrazolidone 27. 3-pyrazolidones as claimed in US. Pat. No. 3,284,200 of the general formual wherein Z is a divalent aliphatic grouping which, with the carbon atoms in 4 and 5 positions of the pyrazolidone ring, completes a five membered or sixmembered cycloaliphatic ring and R is an aryl group e.g., phenyl or naphthyl group. Such aryl groups may be substituted with 'hydroxy, alkoxy, oxyalkyl, amino, substituted amino, nitro, sulphonic or carboxylic groups or halogen atoms. These compounds include, for example, l-phenyl- 4,5-tetramethylene-3-pyrazolidone, l-phenyl-4,5- trimethylene-3-pyrazolidone and l-mchlorophenyl-4,5-tetramethylene-3-pyrazolidone.

The dihydroxybenzene silver halide developing agents which are useful in the developer compositions of this invention are hydroquinone, resorcinol and pyrocatechol.

The following compounds are representative of enediol silver halide developing agents which are useful in the developer compositions of this invention:

1. ascorbic acid 2. d-araboascorbic acid 3. reductic acid 4. enediols as disclosed in US. Pat. No. 3,615,440 are represented by the formula l I c--on R2 C C lene series, at least one of said R R R and R being CH R Tetramethyl reductic acid is one particularly useful enediol.

5. 2-oxytetronic acid 6. 4-aryl-2-oxytetronic acid 7. 4-aryl-2-oxytetronimide 8. isoascorbic acid In addition to the developing agents set forth above, the developer composition includes an inorganic sulfite preservative agent for the developers, such as the sulfites of sodium or potassium; a silver halide solvent, such as sodium or potassium thiocyanate; a graininess reducing salt, such as sodium or lithium chloride; a restrainer, which also serves as a grain reducer, such as sodium or potassium bromide; and a pH buffering agent, such as sodium metaborate, boric acid, acetic acid, sodium carbonate and the like in quantities and combinations sufficient to adjust the developer pH to the desired level within the 8 to 9.5 range.

Optionally, a fourth developing agent selected from the aminophenol class may be employed. The preferred aminophenol (the term aminophenol will be em ployed hereinafter as generic to amino substituted phenols, including diaminophenols for use in the present invention is 2,4 diaminophenol dihydrochloride, commonly known as amidol. However, a number of aminophenol compounds can be used in place of the amidol in the developer of the present invention. It will be appreciated, however, that amidol is the only member of the class that is manufactured and commercially available in quantity.

The following compounds are representative of aminophenol silver halide developing agents which are useful in the developer compositions of this invention:

. p-aminophenol N-methyl-p-aminophenol 2,4-diaminophenol 2,4-diaminoresorcinol 6-methyl-2,4-diaminophenol 5-methyl-2,4-diaminophenol 4-amino-6-methyl-2-methylaminophenol 6-amino-4-methyl-2-methylaminophenol S-dimethylamino-Z-methylaminophenol l0. l,2,4-triaminobenzene l l. S-methyl-l ,2,4-triaminobenzene l2. 4-hydroxy,2',4-diaminodiphenylamine l3. 4,2',4-triaminodiphenylamine l4. l,3-diamino-4,6-dihydroxybenzene It should also be appreciated that the acid salts of any of the foregoing aminophenol agents will likewise be suitable for use in the present developer.

Other optional ingredients include antifoggants such as benzotriazole, borax, which serves both as a fine grain agent and an alkaline buffer; and a water softener where hard water conditions cause flocculation in the developer. Particularly preferred for this latter purpose is sodium hexametaphosphate, which may be provided as the commercially available product Calgon, manufactured by the Calgon Corporation. 5

The primary amines optionally useful in the present invention include ethylamine, monoethanolamine, triethanolamine, ethylenediamine, 2-amino-l-butanol, 2-aminopropanol, 3-aminopropanol and 4.-aminobutanol. Even more desirable are the acid salts of these primary amines formed by reaction with such acids as hydrochloric, nitric, sulfuric, acetic, citric, tartaric, benzoic and ascorbic. Specifically, ethylenediamine sulfate is the preferred amine acid salt component of the developer. The useful concentration range of ethylenediamine sulfate is 0 to 10 grams per liter to contribute the indicated 0 to 4 grams per liter of primary amine. Although Table I shows the amine to be an optional ingredient, when included it is effective to reduce silvering on the film, particularly medium and fast Panchromatic films, caused by the presence of silver halide solvents, such as potassium thiocyanate, in the developer. It should be appreciated, however, that when present the amines contribute added fog density to the developed film.

The following Examples are illustrative of preferred developer compositions within the scope of the present invention.

H O to make 1 liter pH approximately 8.6

EXAMPLE II The developer composition of Example I and a conventional developer, Microdol-X, available commercially from the Eastman Kodak Company, were used to develop the films of Table II after exposure at the listed ASA values (see Table II, column II). The images produced by the Microdol-X exhibited good contrast and density and appeared properly developed. The images produced by the composition of Example I were much too dark (over exposed) and were generally unacceptable.

The films listed in Table II were then exposed at exposure settings progressively greater than the listed ASA and the exposed film developed in both Microdol- X and the composition of Example I until an exposure setting was reached when the images produced by the composition of Example I were comparable in quality (i.e., contrast, density, shadow detail, and the like) to the images produced by the Microdol-X at the listed ASA value for each film. Column ill of Table ll tabulates the exposure settings at which the comparable results were obtained. At the exposure index settings of column III, the images produced by the Microdol-X were extremely thin (under exposed).

Thus development with the developer composition of Example I effectively increased the exposure index of the tested films by a factor of not less than about 3.2 and as high as about 4.2 (column lV) without adversely affecting image quality.

EXAMPLE lll Phenidone 0.86 g/l Hydroquinone 12 g/l Ascorbic Acid 2 g/l Na,SO 50 g/l KSCN 1 g/l NaCl 20 g/l KBr 1% g/l Sodium metaborate 5.7 g

Sodium l-lexametaphosphate 2 R to make l liter pH approximately 8.6

3-pyrazolidone developer 0.8 m 3 grams dihydroxybenzene developer selected from the group consisting of hydroquinone, resorcinol and pyrocatecl ol,..,.. 8to l4 grams enediol developer selected from the group consisting of ascorbic acid, d-araboascorbic acid, reductic acid, 2-oxytetronic acid, 4-aryl-2-oxytetronic acid, 4-aryl-2-oxytetronimide, isoascorbic acidand enediols having the chemical structure represented by the formula R4 OH R.. c c

c oa R2 c c wherein R,, R R and R are selected from the group consisting of hydrogen and the radical CH R R is selected from hydrogen and a monovalent radical selected from the group consisting of amino, cyano, halo, hydroxyl, carboxyl, sulfonyl, alkyl, cycloalkyl, aryl of the benzene or naphthalene series and alkaryl of the benzene or naphthalene series, at least one of said R R R and R being the radical CH2R ..2 to grams inorganic sulfite preservative to 75 grams silver halide solvent selected from sodium and potassium thiocyanate to 2% grams graininess reducer selected from the alkali metal chlorides ..410 30 grams restrainer v. m 2 grams buffering agent 2 to 40 grams.

2. A composition, as claimed in claim 1, wherein said 3-pyrazolidone developer is selected from the developing agents having the following chemical structure:

wherein R R R R and R are selected from hydrogen, alkyl groups containing from l to 4 carbon atoms and aryl groups selected from the benzene and naphthalene series.

3. A composition, as claimed in claim 2, wherein said 3-pyrazolidone is l-phenyl-3-pyrazolidone.

4. A composition, as claimed in claim 1, wherein said enediol is selected from tetramethyl reductic acid and ascorbic acid.

5. A composition, as claimed in claim 1, wherein said dihydroxy-benzene is hydroquinone, said 3- pyrazolidone is l-phenyl-3-pyrazolidone and said enediol is selected from the group consisting of tetramethyl reductic acid and ascorbic acid.

6. A composition, as claimed in claim 5, wherein said inorganic sulfite preservative is selected from sodium and potassium sulfite.

7. A composition, as claimed in claim 5, wherein said graininess reducer is selected from sodium and lithium chloride.

8. A composition, as claimed in claim 5, wherein said restrainer is selected from sodium and potassium bromide.

9. A composition, as claimed in claim 5, wherein said buffering agent is selected from sodium metaborate, boric acid, acetic acid, sodium carbonate and mixtures thereof.

'10. A composition, as claimed in claim 5, wherein said pH is in the range 8.3 8.75.

11. A composition, as claimed in claim 5, further including at least one of the following ingredients:

a. up to 2 grams per liter of an aminophenol developer selected from the group consisting of paminophenol, N-methyl-p-amino phenol, 2,4- diaminophenol, 2,4-diaminoresorcinol, 6-methyl- 2,4-diaminophenol, 5-methyl-2,4-diaminophenol, 4-amino-6-methyl-2-methylaminophenol, 6-amino- 4-methyl-2-methylaminophenol, S-dimethylamino- 2-methylaminophenol, 1,2,4-triaminobenzene, 5- methyl-l,2,4-t:iaminobenzene, 4-hydroxy,2',4- diaminodiphenylamine, 4,2',4'- triaminodiphenylamine, l,3-diamino-4,7- dihydroxybenzene, and the acid salts thereof;

b. up to 4 grams per liter of a primary amine selected from the group consisting of ethylamine, monoethanolamine, triethanolamine, ethylenediamine, 2- amino-l-butanol, 2-aminopropanol, 3- aminopropanol, 4-amino-butanol and the acid salts thereof;

c. up to /2 gram per liter of benzotriazole;

d. up to 4 grams per liter of borax; and

e. up to 2 grams per liter of a water softening agent.

12. A composition, as claimed in claim 11 wherein said additional ingredient is an aminophenol developer selected from the group consisting of p-aminophenol, N-methyl-paminophenol, 2,4-diaminophenol, 2,4- diaminoresorcinol, 6-methyl-2,4-diaminophenol, 5-methyl-2,4-diaminophenol, 4-amino-6-methyl-2- methylaminophenol, 6-amino-4-methyl-2- methylaminophenol, S-dimethylamino-Z- methylaminophenol, l,2,4-triaminobenzene, 5methyl l,2,4-triaminobenzene, 4-hydroxy,2 ,4- diaminodiphenylamine, 4,2',4'- triaminodiphenylamine, l,3-diamino-4,7- dihydroxybenzene, and the acid salts thereof.

13. A composition, as claimed in claim 12, wherein said aminophenol developer is 2,4-diaminophenol dihydrochloride.

14. A composition, as claimed in claim 11 wherein said additional ingredient is a primary amine selected from the group consisting of ethylamine, monoethanolamine, triethanolamine, ethylenediamine, 2-aminolbutanol, 2-aminopropanol, 3-aminopropanol, 4-aminobutanol and the acid salts thereof.

15. A composition, as claimed in claim 14, wherein said primary amine is ethylenediamine sulfate.

16. A composition, as claimed in claim 11, wherein said additional ingredient is benzotriazole.

17. A composition, as claimed in claim 11, wherein said additional ingredient is borax.

18. A composition, as claimed in claim 11, wherein said additional ingredient is a water softening agent.

19. A composition, as claimed in claim 18, wherein said water softening agent is sodium hexametaphosphate.

20. A silver halide photographic developing composition comprising the following ingredients in the weight.

proportion ranges indicated per liter of composition:

l-phenyl-3-pyrazolidone 0.82 gram Hydroq uinone grams Ascorbic Acid 25 grams Na SO 60 grams KSCN 0.5 gram NaCl l2 grams KBr gram Sod. Metaborate 5.6 grams Borax 4 grams Sod. Hexametaphosphate 3 grams.

Water to 1 liter 21. A silver halide photographic developing composition comprising the following ingredients in the weight proportion ranges indicated per liter of composition:

l-phenyl-3-pyrazolidone 0.86 gram Hydroquinone l2 grams Ascorbic Acid 2 grams Na,SO 50 grams KSCN 1 gram NaCl grams KBr V2 gram Sodium metaborate 5.7 grams Sodium Hexametaphosphate 2 grams.

Water to 1 liter 22. A photographic developing process for increasing the exposure index of an imagewise exposed silver halide emulsion film comprising developing said film in an aqueous silver halide photographic developing composition having a pH in the range 8 9.5. said developing composition comprising the following ingredients in the weight proportion ranges indicated per liter of composition:

B-pyrazolidone developer 0.8 to 3 grams dihydroxybenzene developer selected from the group consisting of hydroquinone, resorcinol and pyrocatechol 8 to l4 grams enediol developer selected from the group consisting of ascorbic acid, d-araboascorbic acid, reductic acid, 2-oxytetronic acid, 4-aryl-2-oxytetronic acid, 4-aryl-2-oxytetronimide, isoascorbic acid and enediols having the chemical structure represented by the formula wherein R R R and R, are selected from the group consisting of hydrogen and the radical -Cl-l R R is selected from hydrogen and a monovalent radical selected from the group consisting of amino, cyano, halo, hydroxyl, carboxyl, sulfonyl, alkyl, cycloalkyl, aryl of the benzene or naphthalene series and alkaryl of the benzene or naphthalene series, at least one of said R R R and R being the radical -CH R 2 to 10 grams inorganic sulfite preservative 20 to 75 grams silver halide solvent selected from sodium and potassium thiocyanate A to 2 /2grams graininess reducer selected from the alkali metal chlorides 4 to 30 grams restrainer A; to 2 grams buffering agent 2 to 40 grams. 23. A process, as claimed in claim 22, wherein said 3-pyrazolidone developer is selected from developing agents having the following chemical structure:

H \N/CCIIZR wherein R R R R and R are selected from hydrogen, alkyl groups containing from 1 to 4 carbon atoms and aryl groups selected from the benzene and naphpyrazolidone is l-phenyl-3-pyrazolidone and said enea diol is selected from the group consisting of tetramethyl reductic acid and ascorbic acid.

25. A process, as claimed in claim 24, wherein said pH is in the range 8.3 8.75. i

26. A process, as claimed in claim 24, further including at least one of the following additional ingredients:

a. up to 2 grams per liter of an aminophenol developer selected from the group consisting of p-- 12 amino- 1 -butanol, 2-aminopropanol, 3- aminopropanol, 4-amino-butanol and the acid salts thereof: c. up to /2 gram per liter of rbenzotriazole; (1. up to 4 grams per liter of borax, and e. up to 2 grams per liter of a water softening agent. 27. A process, as claimed in claim 22, wherein said photographic developing composition comprises the following ingredients in the weight proportion ranges indicated per liter of composition:

l-phe nyl-3-pyrazolidone 0.82 gram Hydroquinone 10 grams Ascorbic Acid 2.5 grams Na SO grams KSCN 0.5 gram NaCl 12 grams KBr gram Sod. Metaborate 5.6 grams Borax 4 grams Sod. Hexametaphosphate 3 grams.

Water to 1 liter 

1. A SILVER HALIDE PHOTOGRAPHIC DEVELOPING COMPOSITION HAVING A PH IN THE RANGE 8 - 9.5 COMPRISING THE FOLLOWING INGREDIENTS IN THE WEIGHT PROPORTION RANGES INDICATED PER LITER OF COMPOSITION: 3- PYRAZOLIDONE DEVELOPER...................... 0.8 TO 3 GRAMS DIHYDROXYBENZENE DEVELOPER SELECTED FROM THE GROUP CONSISTING OF HYDROQUINONE, RESORCINOL AND PYROCATECHOL........................................0 TO 14 GRAMS ENEDIOL DEVELOPER SELECTED FROM THE GROUP CONSISTING OF ASCORBIC ACID, D-ARABOASCORBIC ACID, REDUCTIC ACID, 2OXYTETRONIC ACID, 4-ARYL-2-OXYTETRONIC ACID, 4-ARYL-2OXYTETRONIMIDE, ISOASCORBIC ACID AND ENEDIOLS HAVING THE CHEMICAL STRUCTURE REPRESENTED BY THE FORMULA
 2. A composition, as claimed in claim 1, wherein said 3-pyrazolidone developer is selected from the developing agents having the following chemical structure:
 3. A composition, as claimed in claim 2, wherein said 3-pyrazolidone is 1-phenyl-3-pyrazolidone.
 4. A composition, as claimed in claim 1, wherein said enediol is selected from tetramethyl reductic acid and ascorbic acid.
 5. A composition, as claimed in claim 1, wherein said dihydroxy-benzene is hydroquinone, said 3-pyrazolidone is 1-phenyl-3-pyrazolidone and said enediol is selected from the group consisting of tetramethyl reductic acid and ascorbic acid.
 6. A composition, as claimed in claim 5, wherein said inorganic sulfite preservative is selected from sodium and potassium sulfite.
 7. A composition, as claimed in claim 5, wherein said graininess reducer is selected from sodium and lithium chloride.
 8. A composition, as claimed in claim 5, wherein said restrainer is selected from sodium and potassium bromide.
 9. A composition, as claimed in claim 5, wherein said buffering agent is selected from sodium metaborate, boric acid, acetic acid, sodium carbonate and mixtures thereof.
 10. A composition, as claimed in claim 5, wherein said pH is in the range 8.3 - 8.75.
 11. A composition, as claimed in claim 5, further including at least one of the following ingredients: a. up to 2 grams per liter of an aminophenol developer selected from the group consisting of p-aminophenol, N-methyl-p-amino phenol, 2,4-diaminophenol, 2,4-diaminoresorcinol, 6-methyl-2,4-diaminophenol, 5-methyl-2,4-diaminophenol, 4-amino-6-methyl-2-methylaminophenol, 6-amino-4-methyl-2-methylaminophenol, 5-dimethylamino-2-methylaminophenol, 1,2,4-triaminobenzene, 5-methyl-1,2,4-triaminobenzene, 4-hydroxy,2'',4''-diaminodiphenylamine, 4,2'',4''-triaminodiphenylamine, 1,3-diamino-4,7-dihydroxybenzene, and the acid salts thereof; b. up to 4 grams per liter of a primary amine selected from the group consisting of ethylamine, monoethanolamine, triethanolamine, ethylenediamine, 2-amino-1-butanol, 2-aminopropanol, 3-aminopropanol, 4-amino-butanol and the acid salts thereof; c. up to 1/2 gram per liter of benzotriazOle; d. up to 4 grams per liter of borax; and e. up to 2 grams per liter of a water softening agent.
 12. A composition, as claimed in claim 11 wherein said additional ingredient is an aminophenol developer selected from the group consisting of p-aminophenol, N-methyl-p-aminophenol, 2,4-diaminophenol, 2,4-diaminoresorcinol, 6-methyl-2,4-diaminophenol, 5-methyl-2,4-diaminophenol, 4-amino-6-methyl-2-methylaminophenol, 6-amino-4-methyl-2-methylaminophenol, 5-dimethylamino-2-methylaminophenol, 1,2,4-triaminobenzene, 5-methyl-1,2,4-triaminobenzene, 4-hydroxy,2'',4''-diaminodiphenylamine, 4,2'',4''-triaminodiphenylamine, 1,3-diamino-4,7-dihydroxybenzene, and the acid salts thereof.
 13. A composition, as claimed in claim 12, wherein said aminophenol developer is 2,4-diaminophenol dihydrochloride.
 14. A composition, as claimed in claim 11 wherein said additional ingredient is a primary amine selected from the group consisting of ethylamine, monoethanolamine, triethanolamine, ethylenediamine, 2-amino-1-butanol, 2-aminopropanol, 3-aminopropanol, 4-amino-butanol and the acid salts thereof.
 15. A composition, as claimed in claim 14, wherein said primary amine is ethylenediamine sulfate.
 16. A composition, as claimed in claim 11, wherein said additional ingredient is benzotriazole.
 17. A composition, as claimed in claim 11, wherein said additional ingredient is borax.
 18. A composition, as claimed in claim 11, wherein said additional ingredient is a water softening agent.
 19. A composition, as claimed in claim 18, wherein said water softening agent is sodium hexametaphosphate.
 20. A silver halide photographic developing composition comprising the following ingredients in the weight proportion ranges indicated per liter of composition:
 21. A silver halide photographic developing composition comprising the following ingredients in the weight proportion ranges indicated per liter of composition:
 22. A photographic developing process for increasing the exposure index of an imagewise exposed silver halide emulsion film comprising developing said film in an aqueous silver halide photographic developing composition having a pH in the range 8 -9.5, said developing composition comprising the following ingredients in the weight proportion ranges indicated per liter of composition: 3-pyrazolidone developer ... 0.8 to 3 grams dihydroxybenzene developer selected from the group consisting of hydroquinone, resorcinol and pyrocatechol ... 8 to 14 grams enediol developer selected from the group consisting of ascorbic acid, d-araboascorbic acid, reductic acid, 2-oxytetronic acid, 4-aryl-2-oxytetronic acid, 4-aryl-2-oxytetronimide, isoascorbic acid and enediols having the chemical structure represented by the formula
 23. A process, as claimed in claim 22, wherein said 3-pyrazolidone developer is selected from developing agents having the following chemical structure:
 24. A process, as claimed in claim 22, wherein said dihydroxy-benzene is hydroquinone, said 3-pyrazolidone is 1-phenyl-3-pyrazolidone and said enediol is selected from the group consisting of tetramethyl reductic acid and ascorbic acid.
 25. A process, as claimed in claim 24, wherein said pH is in the range 8.3 - 8.75.
 26. A process, as claimed in claim 24, further including at least one of the following additional ingredients: a. up to 2 grams per liter of an aminophenol developer selected from the group consisting of p-aminophenol, N-methyl-p-amino phenol, 2,4-diaminophenol, 2,4-diaminoresorcinol, 6-methyl-2,4-diaminophenol, 5-methyl-2,4-diaminophenol, 4-amino-6-methyl-2-methylaminophenol, 6-amino-4-methyl-2-methylaminophenol, 5-dimethylamino-2-methylaminophenol, 1,2,4-triaminobenzene, 5-methyl-1,2,4-triaminobenzene, 4-hydroxy,2'',4''-diaminodiphenylamine, 4,2'',4''-triaminodiphenylamine, 1,3-diamino-4,7-dihydroxybenzene, and the acid salts thereof; b. up to 4 grams per liter of a primary amine selected from the group consisting of ethylamine, monoethanolamine, triethanolamine ethylenediamine, 2-amino-1-butanol, 2-aminopropanol, 3-aminopropanol, 4-amino-butanol and the acid salts thereof: c. up to 1/2 gram per liter of benzotriazole; d. up to 4 grams per liter of borax, and e. up to 2 grams per liter of a water softening agent.
 27. A process, as claimed in claim 22, wherein said photographic developing composition comprises the following ingredients in the weight proportion ranges indicated per liter of composition: 